Temperature control of the melt as it exits the tip of an injection nozzle is often critical to successful injection molding. If the temperature rises too high degradation of the melt will result and if the temperature falls too low the melt will clog up the system.
One approach to controlling the temperature of the melt at the tip of the nozzle is to divert the melt so that it exits the nozzle tip from a side opening (see for example U.S. Pat. No. 5,658,604 (Gellert)). The melt then collects in a gathering space surrounding the tip before it passes through the mold gate. The advantage of this approach is that the resulting greater mass of the tip below the side opening improves heat transfer from the tip to the melt collecting in the gathering space. A problem with this approach is that the diversion of the melt effects the even flow of the melt through the system. Also, the diversion through a side opening introduces the melt to relatively cooler surfaces of the melt plate that tend to cool the melt excessively.
It is also important that the nozzle tip be located accurately within the nozzle body to ensure that the respective melt channels align. Slight variances in the diameters of the nozzle tips and the bores of the nozzle bodies, or in the thread engagement between the nozzle body and nozzle tip, can lead to slight misalignments of the respective melt channels. Such misalignments can negatively effect the flow of melt through the nozzle.